There are a wide variety of window coverings on the market. Venetian blind 10 (referring to FIG. 1) is one commonly used. It is installed mainly on a door or window to block sunshine and serve ornamental purpose. Depending on users'0 different requirements, the slat assembly 12 of the conventional Venetian blind 10 can be retracted and extended by pulling a lift cord or bead chain, or turned by turning a rotary rod 11. The lift cord or bead chain has the risk of incidentally strangling children and pets. The rotary rod 11 is not aesthetic appealing. It also has different operation approaches for lifting, lowering and turning the slats, hence is more cumbersome to use. All the conventional techniques cannot provide the benefits of a cordless blind.